Difloxacin, also known as 6-fluoro-1-(4-fluorophenyl)-1,4-dihydro-7-(4-methyl-1-piperadinyl) 4-oxo-3-quinolinecarboxylic acid, is an antibiotic compound useful against a wide range of bacteria in animals. However, it is not highly soluble in water, which makes difloxacin difficult to formulate for administration by injection. Difloxacin is soluble in some high pH formulations, but high pH formulations tend to damage or irritate the tissue at the injection site.
U.S. Pat. No. 4,772,605 teaches alkaline aqueous formulations for quinolinecarboxylic acids which contain arginine and a base, and may contain an alcohol and/or other ingredients. Formulations containing difloxacin are not disclosed in this patent.
U.S. Pat. No. 5,756,506 teaches the administration of a single high dose of a fluoroquinolone composition, especially an enrofloxacin composition, for treating bacterial infections in animals.
Japanese patent application no. 232024 (1993), published as no. JP 07082141, discloses an injectable aqueous formulation containing difloxacin, a base, and propylene glycol, and optionally benzyl alcohol. This formulation allegedly reduces tissue damage at the injection site.